/**
 * Copyright (c) 2000-2001 Aaron D. Gifford
 * Copyright (c) 2013-2014 Pavol Rusnak
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holder nor the names of contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTOR(S) ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTOR(S) BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <string.h>
#include <stdint.h>
#include "sha2.h"
#include "memzero.h"
#include "byte_order.h"

/*
 * ASSERT NOTE:
 * Some sanity checking code is included using assert().  On my FreeBSD
 * system, this additional code can be removed by compiling with NDEBUG
 * defined.  Check your own systems manpage on assert() to see how to
 * compile WITHOUT the sanity checking code on your system.
 *
 * UNROLLED TRANSFORM LOOP NOTE:
 * You can define SHA2_UNROLL_TRANSFORM to use the unrolled transform
 * loop version for the hash transform rounds (defined using macros
 * later in this file).  Either define on the command line, for example:
 *
 *   cc -DSHA2_UNROLL_TRANSFORM -o sha2 sha2.c sha2prog.c
 *
 * or define below:
 *
 *   #define SHA2_UNROLL_TRANSFORM
 *
 */

/*** SHA-256/384/512 Machine Architecture Definitions *****************/
/*
 * BYTE_ORDER NOTE:
 *
 * Please make sure that your system defines BYTE_ORDER.  If your
 * architecture is little-endian, make sure it also defines
 * LITTLE_ENDIAN and that the two (BYTE_ORDER and LITTLE_ENDIAN) are
 * equivilent.
 *
 * If your system does not define the above, then you can do so by
 * hand like this:
 *
 *   #define LITTLE_ENDIAN 1234
 *   #define BIG_ENDIAN    4321
 *
 * And for little-endian machines, add:
 *
 *   #define BYTE_ORDER LITTLE_ENDIAN
 *
 * Or for big-endian machines:
 *
 *   #define BYTE_ORDER BIG_ENDIAN
 *
 * The FreeBSD machine this was written on defines BYTE_ORDER
 * appropriately by including <sys/types.h> (which in turn includes
 * <machine/endian.h> where the appropriate definitions are actually
 * made).
 */

#if !defined(BYTE_ORDER) || (BYTE_ORDER != LITTLE_ENDIAN && BYTE_ORDER != BIG_ENDIAN)
#error Define BYTE_ORDER to be equal to either LITTLE_ENDIAN or BIG_ENDIAN
#endif

typedef uint8_t sha2_byte; /* Exactly 1 byte */
typedef uint32_t sha2_word32; /* Exactly 4 bytes */
typedef uint64_t sha2_word64; /* Exactly 8 bytes */

/*** SHA-256/384/512 Various Length Definitions ***********************/
/* NOTE: Most of these are in sha2.h */
#define SHA1_SHORT_BLOCK_LENGTH (SHA1_BLOCK_LENGTH - 8)
#define SHA256_SHORT_BLOCK_LENGTH (SHA256_BLOCK_LENGTH - 8)
#define SHA512_SHORT_BLOCK_LENGTH (SHA512_BLOCK_LENGTH - 16)

/*
 * Macro for incrementally adding the unsigned 64-bit integer n to the
 * unsigned 128-bit integer (represented using a two-element array of
 * 64-bit words):
 */
#define ADDINC128(w, n)             \
    {                               \
        (w)[0] += (sha2_word64)(n); \
        if((w)[0] < (n)) {          \
            (w)[1]++;               \
        }                           \
    }

#define MEMCPY_BCOPY(d, s, l) memcpy((d), (s), (l))

/*** THE SIX LOGICAL FUNCTIONS ****************************************/
/*
 * Bit shifting and rotation (used by the six SHA-XYZ logical functions:
 *
 *   NOTE:  In the original SHA-256/384/512 document, the shift-right
 *   function was named R and the rotate-right function was called S.
 *   (See: http://csrc.nist.gov/cryptval/shs/sha256-384-512.pdf on the
 *   web.)
 *
 *   The newer NIST FIPS 180-2 document uses a much clearer naming
 *   scheme, SHR for shift-right, ROTR for rotate-right, and ROTL for
 *   rotate-left.  (See:
 *   http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
 *   on the web.)
 *
 *   WARNING: These macros must be used cautiously, since they reference
 *   supplied parameters sometimes more than once, and thus could have
 *   unexpected side-effects if used without taking this into account.
 */

/* Shift-right (used in SHA-256, SHA-384, and SHA-512): */
#define SHR(b, x) ((x) >> (b))
/* 32-bit Rotate-right (used in SHA-256): */
#define ROTR32(b, x) (((x) >> (b)) | ((x) << (32 - (b))))
/* 64-bit Rotate-right (used in SHA-384 and SHA-512): */
#define ROTR64(b, x) (((x) >> (b)) | ((x) << (64 - (b))))
/* 32-bit Rotate-left (used in SHA-1): */
#define ROTL32(b, x) (((x) << (b)) | ((x) >> (32 - (b))))

/* Two of six logical functions used in SHA-1, SHA-256, SHA-384, and SHA-512: */
#define Ch(x, y, z) (((x) & (y)) ^ ((~(x)) & (z)))
#define Maj(x, y, z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))

/* Function used in SHA-1: */
#define Parity(x, y, z) ((x) ^ (y) ^ (z))

/* Four of six logical functions used in SHA-256: */
#define Sigma0_256(x) (ROTR32(2, (x)) ^ ROTR32(13, (x)) ^ ROTR32(22, (x)))
#define Sigma1_256(x) (ROTR32(6, (x)) ^ ROTR32(11, (x)) ^ ROTR32(25, (x)))
#define sigma0_256(x) (ROTR32(7, (x)) ^ ROTR32(18, (x)) ^ SHR(3, (x)))
#define sigma1_256(x) (ROTR32(17, (x)) ^ ROTR32(19, (x)) ^ SHR(10, (x)))

/* Four of six logical functions used in SHA-384 and SHA-512: */
#define Sigma0_512(x) (ROTR64(28, (x)) ^ ROTR64(34, (x)) ^ ROTR64(39, (x)))
#define Sigma1_512(x) (ROTR64(14, (x)) ^ ROTR64(18, (x)) ^ ROTR64(41, (x)))
#define sigma0_512(x) (ROTR64(1, (x)) ^ ROTR64(8, (x)) ^ SHR(7, (x)))
#define sigma1_512(x) (ROTR64(19, (x)) ^ ROTR64(61, (x)) ^ SHR(6, (x)))

/*** INTERNAL FUNCTION PROTOTYPES *************************************/
/* NOTE: These should not be accessed directly from outside this
 * library -- they are intended for private internal visibility/use
 * only.
 */
static void sha512_Last(SHA512_CTX*);

/*** SHA-XYZ INITIAL HASH VALUES AND CONSTANTS ************************/

/* Hash constant words K for SHA-1: */
#define K1_0_TO_19 0x5a827999UL
#define K1_20_TO_39 0x6ed9eba1UL
#define K1_40_TO_59 0x8f1bbcdcUL
#define K1_60_TO_79 0xca62c1d6UL

/* Initial hash value H for SHA-1: */
const sha2_word32 sha1_initial_hash_value[SHA1_DIGEST_LENGTH / sizeof(sha2_word32)] =
    {0x67452301UL, 0xefcdab89UL, 0x98badcfeUL, 0x10325476UL, 0xc3d2e1f0UL};

/* Hash constant words K for SHA-256: */
static const sha2_word32 K256[64] = {
    0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL, 0x3956c25bUL, 0x59f111f1UL,
    0x923f82a4UL, 0xab1c5ed5UL, 0xd807aa98UL, 0x12835b01UL, 0x243185beUL, 0x550c7dc3UL,
    0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL, 0xc19bf174UL, 0xe49b69c1UL, 0xefbe4786UL,
    0x0fc19dc6UL, 0x240ca1ccUL, 0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL,
    0x983e5152UL, 0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL, 0xc6e00bf3UL, 0xd5a79147UL,
    0x06ca6351UL, 0x14292967UL, 0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL, 0x53380d13UL,
    0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL, 0xa2bfe8a1UL, 0xa81a664bUL,
    0xc24b8b70UL, 0xc76c51a3UL, 0xd192e819UL, 0xd6990624UL, 0xf40e3585UL, 0x106aa070UL,
    0x19a4c116UL, 0x1e376c08UL, 0x2748774cUL, 0x34b0bcb5UL, 0x391c0cb3UL, 0x4ed8aa4aUL,
    0x5b9cca4fUL, 0x682e6ff3UL, 0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
    0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL};

/* Initial hash value H for SHA-256: */
const sha2_word32 sha256_initial_hash_value[8] = {
    0x6a09e667UL,
    0xbb67ae85UL,
    0x3c6ef372UL,
    0xa54ff53aUL,
    0x510e527fUL,
    0x9b05688cUL,
    0x1f83d9abUL,
    0x5be0cd19UL};

/* Hash constant words K for SHA-384 and SHA-512: */
static const sha2_word64 K512[80] = {
    0x428a2f98d728ae22ULL, 0x7137449123ef65cdULL, 0xb5c0fbcfec4d3b2fULL, 0xe9b5dba58189dbbcULL,
    0x3956c25bf348b538ULL, 0x59f111f1b605d019ULL, 0x923f82a4af194f9bULL, 0xab1c5ed5da6d8118ULL,
    0xd807aa98a3030242ULL, 0x12835b0145706fbeULL, 0x243185be4ee4b28cULL, 0x550c7dc3d5ffb4e2ULL,
    0x72be5d74f27b896fULL, 0x80deb1fe3b1696b1ULL, 0x9bdc06a725c71235ULL, 0xc19bf174cf692694ULL,
    0xe49b69c19ef14ad2ULL, 0xefbe4786384f25e3ULL, 0x0fc19dc68b8cd5b5ULL, 0x240ca1cc77ac9c65ULL,
    0x2de92c6f592b0275ULL, 0x4a7484aa6ea6e483ULL, 0x5cb0a9dcbd41fbd4ULL, 0x76f988da831153b5ULL,
    0x983e5152ee66dfabULL, 0xa831c66d2db43210ULL, 0xb00327c898fb213fULL, 0xbf597fc7beef0ee4ULL,
    0xc6e00bf33da88fc2ULL, 0xd5a79147930aa725ULL, 0x06ca6351e003826fULL, 0x142929670a0e6e70ULL,
    0x27b70a8546d22ffcULL, 0x2e1b21385c26c926ULL, 0x4d2c6dfc5ac42aedULL, 0x53380d139d95b3dfULL,
    0x650a73548baf63deULL, 0x766a0abb3c77b2a8ULL, 0x81c2c92e47edaee6ULL, 0x92722c851482353bULL,
    0xa2bfe8a14cf10364ULL, 0xa81a664bbc423001ULL, 0xc24b8b70d0f89791ULL, 0xc76c51a30654be30ULL,
    0xd192e819d6ef5218ULL, 0xd69906245565a910ULL, 0xf40e35855771202aULL, 0x106aa07032bbd1b8ULL,
    0x19a4c116b8d2d0c8ULL, 0x1e376c085141ab53ULL, 0x2748774cdf8eeb99ULL, 0x34b0bcb5e19b48a8ULL,
    0x391c0cb3c5c95a63ULL, 0x4ed8aa4ae3418acbULL, 0x5b9cca4f7763e373ULL, 0x682e6ff3d6b2b8a3ULL,
    0x748f82ee5defb2fcULL, 0x78a5636f43172f60ULL, 0x84c87814a1f0ab72ULL, 0x8cc702081a6439ecULL,
    0x90befffa23631e28ULL, 0xa4506cebde82bde9ULL, 0xbef9a3f7b2c67915ULL, 0xc67178f2e372532bULL,
    0xca273eceea26619cULL, 0xd186b8c721c0c207ULL, 0xeada7dd6cde0eb1eULL, 0xf57d4f7fee6ed178ULL,
    0x06f067aa72176fbaULL, 0x0a637dc5a2c898a6ULL, 0x113f9804bef90daeULL, 0x1b710b35131c471bULL,
    0x28db77f523047d84ULL, 0x32caab7b40c72493ULL, 0x3c9ebe0a15c9bebcULL, 0x431d67c49c100d4cULL,
    0x4cc5d4becb3e42b6ULL, 0x597f299cfc657e2aULL, 0x5fcb6fab3ad6faecULL, 0x6c44198c4a475817ULL};

/* Initial hash value H for SHA-512 */
const sha2_word64 sha512_initial_hash_value[8] = {
    0x6a09e667f3bcc908ULL,
    0xbb67ae8584caa73bULL,
    0x3c6ef372fe94f82bULL,
    0xa54ff53a5f1d36f1ULL,
    0x510e527fade682d1ULL,
    0x9b05688c2b3e6c1fULL,
    0x1f83d9abfb41bd6bULL,
    0x5be0cd19137e2179ULL};

/*
 * Constant used by SHA256/384/512_End() functions for converting the
 * digest to a readable hexadecimal character string:
 */
static const char* sha2_hex_digits = "0123456789abcdef";

/*** SHA-1: ***********************************************************/
void sha1_Init(SHA1_CTX* context) {
    MEMCPY_BCOPY(context->state, sha1_initial_hash_value, SHA1_DIGEST_LENGTH);
    memzero(context->buffer, SHA1_BLOCK_LENGTH);
    context->bitcount = 0;
}

#ifdef SHA2_UNROLL_TRANSFORM

/* Unrolled SHA-1 round macros: */

#define ROUND1_0_TO_15(a, b, c, d, e)                                                \
    (e) = ROTL32(5, (a)) + Ch((b), (c), (d)) + (e) + K1_0_TO_19 + (W1[j] = *data++); \
    (b) = ROTL32(30, (b));                                                           \
    j++;

#define ROUND1_16_TO_19(a, b, c, d, e)                                                  \
    T1 = W1[(j + 13) & 0x0f] ^ W1[(j + 8) & 0x0f] ^ W1[(j + 2) & 0x0f] ^ W1[j & 0x0f];  \
    (e) = ROTL32(5, a) + Ch(b, c, d) + e + K1_0_TO_19 + (W1[j & 0x0f] = ROTL32(1, T1)); \
    (b) = ROTL32(30, b);                                                                \
    j++;

#define ROUND1_20_TO_39(a, b, c, d, e)                                                       \
    T1 = W1[(j + 13) & 0x0f] ^ W1[(j + 8) & 0x0f] ^ W1[(j + 2) & 0x0f] ^ W1[j & 0x0f];       \
    (e) = ROTL32(5, a) + Parity(b, c, d) + e + K1_20_TO_39 + (W1[j & 0x0f] = ROTL32(1, T1)); \
    (b) = ROTL32(30, b);                                                                     \
    j++;

#define ROUND1_40_TO_59(a, b, c, d, e)                                                    \
    T1 = W1[(j + 13) & 0x0f] ^ W1[(j + 8) & 0x0f] ^ W1[(j + 2) & 0x0f] ^ W1[j & 0x0f];    \
    (e) = ROTL32(5, a) + Maj(b, c, d) + e + K1_40_TO_59 + (W1[j & 0x0f] = ROTL32(1, T1)); \
    (b) = ROTL32(30, b);                                                                  \
    j++;

#define ROUND1_60_TO_79(a, b, c, d, e)                                                       \
    T1 = W1[(j + 13) & 0x0f] ^ W1[(j + 8) & 0x0f] ^ W1[(j + 2) & 0x0f] ^ W1[j & 0x0f];       \
    (e) = ROTL32(5, a) + Parity(b, c, d) + e + K1_60_TO_79 + (W1[j & 0x0f] = ROTL32(1, T1)); \
    (b) = ROTL32(30, b);                                                                     \
    j++;

void sha1_Transform(const sha2_word32* state_in, const sha2_word32* data, sha2_word32* state_out) {
    sha2_word32 a = 0, b = 0, c = 0, d = 0, e = 0;
    sha2_word32 T1 = 0;
    sha2_word32 W1[16] = {0};
    int j = 0;

    /* Initialize registers with the prev. intermediate value */
    a = state_in[0];
    b = state_in[1];
    c = state_in[2];
    d = state_in[3];
    e = state_in[4];

    j = 0;

    /* Rounds 0 to 15 unrolled: */
    ROUND1_0_TO_15(a, b, c, d, e);
    ROUND1_0_TO_15(e, a, b, c, d);
    ROUND1_0_TO_15(d, e, a, b, c);
    ROUND1_0_TO_15(c, d, e, a, b);
    ROUND1_0_TO_15(b, c, d, e, a);
    ROUND1_0_TO_15(a, b, c, d, e);
    ROUND1_0_TO_15(e, a, b, c, d);
    ROUND1_0_TO_15(d, e, a, b, c);
    ROUND1_0_TO_15(c, d, e, a, b);
    ROUND1_0_TO_15(b, c, d, e, a);
    ROUND1_0_TO_15(a, b, c, d, e);
    ROUND1_0_TO_15(e, a, b, c, d);
    ROUND1_0_TO_15(d, e, a, b, c);
    ROUND1_0_TO_15(c, d, e, a, b);
    ROUND1_0_TO_15(b, c, d, e, a);
    ROUND1_0_TO_15(a, b, c, d, e);

    /* Rounds 16 to 19 unrolled: */
    ROUND1_16_TO_19(e, a, b, c, d);
    ROUND1_16_TO_19(d, e, a, b, c);
    ROUND1_16_TO_19(c, d, e, a, b);
    ROUND1_16_TO_19(b, c, d, e, a);

    /* Rounds 20 to 39 unrolled: */
    ROUND1_20_TO_39(a, b, c, d, e);
    ROUND1_20_TO_39(e, a, b, c, d);
    ROUND1_20_TO_39(d, e, a, b, c);
    ROUND1_20_TO_39(c, d, e, a, b);
    ROUND1_20_TO_39(b, c, d, e, a);
    ROUND1_20_TO_39(a, b, c, d, e);
    ROUND1_20_TO_39(e, a, b, c, d);
    ROUND1_20_TO_39(d, e, a, b, c);
    ROUND1_20_TO_39(c, d, e, a, b);
    ROUND1_20_TO_39(b, c, d, e, a);
    ROUND1_20_TO_39(a, b, c, d, e);
    ROUND1_20_TO_39(e, a, b, c, d);
    ROUND1_20_TO_39(d, e, a, b, c);
    ROUND1_20_TO_39(c, d, e, a, b);
    ROUND1_20_TO_39(b, c, d, e, a);
    ROUND1_20_TO_39(a, b, c, d, e);
    ROUND1_20_TO_39(e, a, b, c, d);
    ROUND1_20_TO_39(d, e, a, b, c);
    ROUND1_20_TO_39(c, d, e, a, b);
    ROUND1_20_TO_39(b, c, d, e, a);

    /* Rounds 40 to 59 unrolled: */
    ROUND1_40_TO_59(a, b, c, d, e);
    ROUND1_40_TO_59(e, a, b, c, d);
    ROUND1_40_TO_59(d, e, a, b, c);
    ROUND1_40_TO_59(c, d, e, a, b);
    ROUND1_40_TO_59(b, c, d, e, a);
    ROUND1_40_TO_59(a, b, c, d, e);
    ROUND1_40_TO_59(e, a, b, c, d);
    ROUND1_40_TO_59(d, e, a, b, c);
    ROUND1_40_TO_59(c, d, e, a, b);
    ROUND1_40_TO_59(b, c, d, e, a);
    ROUND1_40_TO_59(a, b, c, d, e);
    ROUND1_40_TO_59(e, a, b, c, d);
    ROUND1_40_TO_59(d, e, a, b, c);
    ROUND1_40_TO_59(c, d, e, a, b);
    ROUND1_40_TO_59(b, c, d, e, a);
    ROUND1_40_TO_59(a, b, c, d, e);
    ROUND1_40_TO_59(e, a, b, c, d);
    ROUND1_40_TO_59(d, e, a, b, c);
    ROUND1_40_TO_59(c, d, e, a, b);
    ROUND1_40_TO_59(b, c, d, e, a);

    /* Rounds 60 to 79 unrolled: */
    ROUND1_60_TO_79(a, b, c, d, e);
    ROUND1_60_TO_79(e, a, b, c, d);
    ROUND1_60_TO_79(d, e, a, b, c);
    ROUND1_60_TO_79(c, d, e, a, b);
    ROUND1_60_TO_79(b, c, d, e, a);
    ROUND1_60_TO_79(a, b, c, d, e);
    ROUND1_60_TO_79(e, a, b, c, d);
    ROUND1_60_TO_79(d, e, a, b, c);
    ROUND1_60_TO_79(c, d, e, a, b);
    ROUND1_60_TO_79(b, c, d, e, a);
    ROUND1_60_TO_79(a, b, c, d, e);
    ROUND1_60_TO_79(e, a, b, c, d);
    ROUND1_60_TO_79(d, e, a, b, c);
    ROUND1_60_TO_79(c, d, e, a, b);
    ROUND1_60_TO_79(b, c, d, e, a);
    ROUND1_60_TO_79(a, b, c, d, e);
    ROUND1_60_TO_79(e, a, b, c, d);
    ROUND1_60_TO_79(d, e, a, b, c);
    ROUND1_60_TO_79(c, d, e, a, b);
    ROUND1_60_TO_79(b, c, d, e, a);

    /* Compute the current intermediate hash value */
    state_out[0] = state_in[0] + a;
    state_out[1] = state_in[1] + b;
    state_out[2] = state_in[2] + c;
    state_out[3] = state_in[3] + d;
    state_out[4] = state_in[4] + e;

    /* Clean up */
    a = b = c = d = e = T1 = 0;
}

#else /* SHA2_UNROLL_TRANSFORM */

void sha1_Transform(const sha2_word32* state_in, const sha2_word32* data, sha2_word32* state_out) {
    sha2_word32 a = 0, b = 0, c = 0, d = 0, e = 0;
    sha2_word32 T1 = 0;
    sha2_word32 W1[16] = {0};
    int j = 0;

    /* Initialize registers with the prev. intermediate value */
    a = state_in[0];
    b = state_in[1];
    c = state_in[2];
    d = state_in[3];
    e = state_in[4];
    j = 0;
    do {
        T1 = ROTL32(5, a) + Ch(b, c, d) + e + K1_0_TO_19 + (W1[j] = *data++);
        e = d;
        d = c;
        c = ROTL32(30, b);
        b = a;
        a = T1;
        j++;
    } while(j < 16);

    do {
        T1 = W1[(j + 13) & 0x0f] ^ W1[(j + 8) & 0x0f] ^ W1[(j + 2) & 0x0f] ^ W1[j & 0x0f];
        T1 = ROTL32(5, a) + Ch(b, c, d) + e + K1_0_TO_19 + (W1[j & 0x0f] = ROTL32(1, T1));
        e = d;
        d = c;
        c = ROTL32(30, b);
        b = a;
        a = T1;
        j++;
    } while(j < 20);

    do {
        T1 = W1[(j + 13) & 0x0f] ^ W1[(j + 8) & 0x0f] ^ W1[(j + 2) & 0x0f] ^ W1[j & 0x0f];
        T1 = ROTL32(5, a) + Parity(b, c, d) + e + K1_20_TO_39 + (W1[j & 0x0f] = ROTL32(1, T1));
        e = d;
        d = c;
        c = ROTL32(30, b);
        b = a;
        a = T1;
        j++;
    } while(j < 40);

    do {
        T1 = W1[(j + 13) & 0x0f] ^ W1[(j + 8) & 0x0f] ^ W1[(j + 2) & 0x0f] ^ W1[j & 0x0f];
        T1 = ROTL32(5, a) + Maj(b, c, d) + e + K1_40_TO_59 + (W1[j & 0x0f] = ROTL32(1, T1));
        e = d;
        d = c;
        c = ROTL32(30, b);
        b = a;
        a = T1;
        j++;
    } while(j < 60);

    do {
        T1 = W1[(j + 13) & 0x0f] ^ W1[(j + 8) & 0x0f] ^ W1[(j + 2) & 0x0f] ^ W1[j & 0x0f];
        T1 = ROTL32(5, a) + Parity(b, c, d) + e + K1_60_TO_79 + (W1[j & 0x0f] = ROTL32(1, T1));
        e = d;
        d = c;
        c = ROTL32(30, b);
        b = a;
        a = T1;
        j++;
    } while(j < 80);

    /* Compute the current intermediate hash value */
    state_out[0] = state_in[0] + a;
    state_out[1] = state_in[1] + b;
    state_out[2] = state_in[2] + c;
    state_out[3] = state_in[3] + d;
    state_out[4] = state_in[4] + e;

    /* Clean up */
    a = b = c = d = e = T1 = 0;
}

#endif /* SHA2_UNROLL_TRANSFORM */

void sha1_Update(SHA1_CTX* context, const sha2_byte* data, size_t len) {
    unsigned int freespace = 0, usedspace = 0;

    if(len == 0) {
        /* Calling with no data is valid - we do nothing */
        return;
    }

    usedspace = (context->bitcount >> 3) % SHA1_BLOCK_LENGTH;
    if(usedspace > 0) {
        /* Calculate how much free space is available in the buffer */
        freespace = SHA1_BLOCK_LENGTH - usedspace;

        if(len >= freespace) {
            /* Fill the buffer completely and process it */
            MEMCPY_BCOPY(((uint8_t*)context->buffer) + usedspace, data, freespace);
            context->bitcount += freespace << 3;
            len -= freespace;
            data += freespace;
#if BYTE_ORDER == LITTLE_ENDIAN
            /* Convert TO host byte order */
            for(int j = 0; j < 16; j++) {
                REVERSE32(context->buffer[j], context->buffer[j]);
            }
#endif
            sha1_Transform(context->state, context->buffer, context->state);
        } else {
            /* The buffer is not yet full */
            MEMCPY_BCOPY(((uint8_t*)context->buffer) + usedspace, data, len);
            context->bitcount += len << 3;
            /* Clean up: */
            usedspace = freespace = 0;
            return;
        }
    }
    while(len >= SHA1_BLOCK_LENGTH) {
        /* Process as many complete blocks as we can */
        MEMCPY_BCOPY(context->buffer, data, SHA1_BLOCK_LENGTH);
#if BYTE_ORDER == LITTLE_ENDIAN
        /* Convert TO host byte order */
        for(int j = 0; j < 16; j++) {
            REVERSE32(context->buffer[j], context->buffer[j]);
        }
#endif
        sha1_Transform(context->state, context->buffer, context->state);
        context->bitcount += SHA1_BLOCK_LENGTH << 3;
        len -= SHA1_BLOCK_LENGTH;
        data += SHA1_BLOCK_LENGTH;
    }
    if(len > 0) {
        /* There's left-overs, so save 'em */
        MEMCPY_BCOPY(context->buffer, data, len);
        context->bitcount += len << 3;
    }
    /* Clean up: */
    usedspace = freespace = 0;
}

void sha1_Final(SHA1_CTX* context, sha2_byte digest[SHA1_DIGEST_LENGTH]) {
    unsigned int usedspace = 0;

    /* If no digest buffer is passed, we don't bother doing this: */
    if(digest != (sha2_byte*)0) {
        usedspace = (context->bitcount >> 3) % SHA1_BLOCK_LENGTH;
        /* Begin padding with a 1 bit: */
        ((uint8_t*)context->buffer)[usedspace++] = 0x80;

        if(usedspace > SHA1_SHORT_BLOCK_LENGTH) {
            memzero(((uint8_t*)context->buffer) + usedspace, SHA1_BLOCK_LENGTH - usedspace);

#if BYTE_ORDER == LITTLE_ENDIAN
            /* Convert TO host byte order */
            for(int j = 0; j < 16; j++) {
                REVERSE32(context->buffer[j], context->buffer[j]);
            }
#endif
            /* Do second-to-last transform: */
            sha1_Transform(context->state, context->buffer, context->state);

            /* And prepare the last transform: */
            usedspace = 0;
        }
        /* Set-up for the last transform: */
        memzero(((uint8_t*)context->buffer) + usedspace, SHA1_SHORT_BLOCK_LENGTH - usedspace);

#if BYTE_ORDER == LITTLE_ENDIAN
        /* Convert TO host byte order */
        for(int j = 0; j < 14; j++) {
            REVERSE32(context->buffer[j], context->buffer[j]);
        }
#endif
        /* Set the bit count: */
        context->buffer[14] = context->bitcount >> 32;
        context->buffer[15] = context->bitcount & 0xffffffff;

        /* Final transform: */
        sha1_Transform(context->state, context->buffer, context->state);

#if BYTE_ORDER == LITTLE_ENDIAN
        /* Convert FROM host byte order */
        for(int j = 0; j < 5; j++) {
            REVERSE32(context->state[j], context->state[j]);
        }
#endif
        MEMCPY_BCOPY(digest, context->state, SHA1_DIGEST_LENGTH);
    }

    /* Clean up state data: */
    memzero(context, sizeof(SHA1_CTX));
    usedspace = 0;
}

char* sha1_End(SHA1_CTX* context, char buffer[SHA1_DIGEST_STRING_LENGTH]) {
    sha2_byte digest[SHA1_DIGEST_LENGTH] = {0}, *d = digest;
    int i = 0;

    if(buffer != (char*)0) {
        sha1_Final(context, digest);

        for(i = 0; i < SHA1_DIGEST_LENGTH; i++) {
            *buffer++ = sha2_hex_digits[(*d & 0xf0) >> 4];
            *buffer++ = sha2_hex_digits[*d & 0x0f];
            d++;
        }
        *buffer = (char)0;
    } else {
        memzero(context, sizeof(SHA1_CTX));
    }
    memzero(digest, SHA1_DIGEST_LENGTH);
    return buffer;
}

void sha1_Raw(const sha2_byte* data, size_t len, uint8_t digest[SHA1_DIGEST_LENGTH]) {
    SHA1_CTX context = {0};
    sha1_Init(&context);
    sha1_Update(&context, data, len);
    sha1_Final(&context, digest);
}

char* sha1_Data(const sha2_byte* data, size_t len, char digest[SHA1_DIGEST_STRING_LENGTH]) {
    SHA1_CTX context = {0};

    sha1_Init(&context);
    sha1_Update(&context, data, len);
    return sha1_End(&context, digest);
}

/*** SHA-256: *********************************************************/
void sha256_Init(SHA256_CTX* context) {
    if(context == (SHA256_CTX*)0) {
        return;
    }
    MEMCPY_BCOPY(context->state, sha256_initial_hash_value, SHA256_DIGEST_LENGTH);
    memzero(context->buffer, SHA256_BLOCK_LENGTH);
    context->bitcount = 0;
}

void sha256_Init_ex(SHA256_CTX* context, const uint32_t state[8], uint64_t bitcount) {
    if(context == (SHA256_CTX*)0) {
        return;
    }
    MEMCPY_BCOPY(context->state, state, SHA256_DIGEST_LENGTH);
    memzero(context->buffer, SHA256_BLOCK_LENGTH);
    context->bitcount = bitcount;
}

#ifdef SHA2_UNROLL_TRANSFORM

/* Unrolled SHA-256 round macros: */

#define ROUND256_0_TO_15(a, b, c, d, e, f, g, h)                                  \
    T1 = (h) + Sigma1_256(e) + Ch((e), (f), (g)) + K256[j] + (W256[j] = *data++); \
    (d) += T1;                                                                    \
    (h) = T1 + Sigma0_256(a) + Maj((a), (b), (c));                                \
    j++

#define ROUND256(a, b, c, d, e, f, g, h)                     \
    s0 = W256[(j + 1) & 0x0f];                               \
    s0 = sigma0_256(s0);                                     \
    s1 = W256[(j + 14) & 0x0f];                              \
    s1 = sigma1_256(s1);                                     \
    T1 = (h) + Sigma1_256(e) + Ch((e), (f), (g)) + K256[j] + \
         (W256[j & 0x0f] += s1 + W256[(j + 9) & 0x0f] + s0); \
    (d) += T1;                                               \
    (h) = T1 + Sigma0_256(a) + Maj((a), (b), (c));           \
    j++

void sha256_Transform(const sha2_word32* state_in, const sha2_word32* data, sha2_word32* state_out) {
    sha2_word32 a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, s0 = 0, s1 = 0;
    sha2_word32 T1 = 0;
    sha2_word32 W256[16] = {0};
    int j = 0;

    /* Initialize registers with the prev. intermediate value */
    a = state_in[0];
    b = state_in[1];
    c = state_in[2];
    d = state_in[3];
    e = state_in[4];
    f = state_in[5];
    g = state_in[6];
    h = state_in[7];

    j = 0;
    do {
        /* Rounds 0 to 15 (unrolled): */
        ROUND256_0_TO_15(a, b, c, d, e, f, g, h);
        ROUND256_0_TO_15(h, a, b, c, d, e, f, g);
        ROUND256_0_TO_15(g, h, a, b, c, d, e, f);
        ROUND256_0_TO_15(f, g, h, a, b, c, d, e);
        ROUND256_0_TO_15(e, f, g, h, a, b, c, d);
        ROUND256_0_TO_15(d, e, f, g, h, a, b, c);
        ROUND256_0_TO_15(c, d, e, f, g, h, a, b);
        ROUND256_0_TO_15(b, c, d, e, f, g, h, a);
    } while(j < 16);

    /* Now for the remaining rounds to 64: */
    do {
        ROUND256(a, b, c, d, e, f, g, h);
        ROUND256(h, a, b, c, d, e, f, g);
        ROUND256(g, h, a, b, c, d, e, f);
        ROUND256(f, g, h, a, b, c, d, e);
        ROUND256(e, f, g, h, a, b, c, d);
        ROUND256(d, e, f, g, h, a, b, c);
        ROUND256(c, d, e, f, g, h, a, b);
        ROUND256(b, c, d, e, f, g, h, a);
    } while(j < 64);

    /* Compute the current intermediate hash value */
    state_out[0] = state_in[0] + a;
    state_out[1] = state_in[1] + b;
    state_out[2] = state_in[2] + c;
    state_out[3] = state_in[3] + d;
    state_out[4] = state_in[4] + e;
    state_out[5] = state_in[5] + f;
    state_out[6] = state_in[6] + g;
    state_out[7] = state_in[7] + h;

    /* Clean up */
    a = b = c = d = e = f = g = h = T1 = 0;
}

#else /* SHA2_UNROLL_TRANSFORM */

void sha256_Transform(const sha2_word32* state_in, const sha2_word32* data, sha2_word32* state_out) {
    sha2_word32 a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, s0 = 0, s1 = 0;
    sha2_word32 T1 = 0, T2 = 0, W256[16] = {0};
    int j = 0;

    /* Initialize registers with the prev. intermediate value */
    a = state_in[0];
    b = state_in[1];
    c = state_in[2];
    d = state_in[3];
    e = state_in[4];
    f = state_in[5];
    g = state_in[6];
    h = state_in[7];

    j = 0;
    do {
        /* Apply the SHA-256 compression function to update a..h with copy */
        T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] + (W256[j] = *data++);
        T2 = Sigma0_256(a) + Maj(a, b, c);
        h = g;
        g = f;
        f = e;
        e = d + T1;
        d = c;
        c = b;
        b = a;
        a = T1 + T2;

        j++;
    } while(j < 16);

    do {
        /* Part of the message block expansion: */
        s0 = W256[(j + 1) & 0x0f];
        s0 = sigma0_256(s0);
        s1 = W256[(j + 14) & 0x0f];
        s1 = sigma1_256(s1);

        /* Apply the SHA-256 compression function to update a..h */
        T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] +
             (W256[j & 0x0f] += s1 + W256[(j + 9) & 0x0f] + s0);
        T2 = Sigma0_256(a) + Maj(a, b, c);
        h = g;
        g = f;
        f = e;
        e = d + T1;
        d = c;
        c = b;
        b = a;
        a = T1 + T2;

        j++;
    } while(j < 64);

    /* Compute the current intermediate hash value */
    state_out[0] = state_in[0] + a;
    state_out[1] = state_in[1] + b;
    state_out[2] = state_in[2] + c;
    state_out[3] = state_in[3] + d;
    state_out[4] = state_in[4] + e;
    state_out[5] = state_in[5] + f;
    state_out[6] = state_in[6] + g;
    state_out[7] = state_in[7] + h;

    /* Clean up */
    a = b = c = d = e = f = g = h = T1 = T2 = 0;
}

#endif /* SHA2_UNROLL_TRANSFORM */

void sha256_Update(SHA256_CTX* context, const sha2_byte* data, size_t len) {
    unsigned int freespace = 0, usedspace = 0;

    if(len == 0) {
        /* Calling with no data is valid - we do nothing */
        return;
    }

    usedspace = (context->bitcount >> 3) % SHA256_BLOCK_LENGTH;
    if(usedspace > 0) {
        /* Calculate how much free space is available in the buffer */
        freespace = SHA256_BLOCK_LENGTH - usedspace;

        if(len >= freespace) {
            /* Fill the buffer completely and process it */
            MEMCPY_BCOPY(((uint8_t*)context->buffer) + usedspace, data, freespace);
            context->bitcount += freespace << 3;
            len -= freespace;
            data += freespace;
#if BYTE_ORDER == LITTLE_ENDIAN
            /* Convert TO host byte order */
            for(int j = 0; j < 16; j++) {
                REVERSE32(context->buffer[j], context->buffer[j]);
            }
#endif
            sha256_Transform(context->state, context->buffer, context->state);
        } else {
            /* The buffer is not yet full */
            MEMCPY_BCOPY(((uint8_t*)context->buffer) + usedspace, data, len);
            context->bitcount += len << 3;
            /* Clean up: */
            usedspace = freespace = 0;
            return;
        }
    }
    while(len >= SHA256_BLOCK_LENGTH) {
        /* Process as many complete blocks as we can */
        MEMCPY_BCOPY(context->buffer, data, SHA256_BLOCK_LENGTH);
#if BYTE_ORDER == LITTLE_ENDIAN
        /* Convert TO host byte order */
        for(int j = 0; j < 16; j++) {
            REVERSE32(context->buffer[j], context->buffer[j]);
        }
#endif
        sha256_Transform(context->state, context->buffer, context->state);
        context->bitcount += SHA256_BLOCK_LENGTH << 3;
        len -= SHA256_BLOCK_LENGTH;
        data += SHA256_BLOCK_LENGTH;
    }
    if(len > 0) {
        /* There's left-overs, so save 'em */
        MEMCPY_BCOPY(context->buffer, data, len);
        context->bitcount += len << 3;
    }
    /* Clean up: */
    usedspace = freespace = 0;
}

void sha256_Final(SHA256_CTX* context, sha2_byte digest[SHA256_DIGEST_LENGTH]) {
    unsigned int usedspace = 0;

    /* If no digest buffer is passed, we don't bother doing this: */
    if(digest != (sha2_byte*)0) {
        usedspace = (context->bitcount >> 3) % SHA256_BLOCK_LENGTH;
        /* Begin padding with a 1 bit: */
        ((uint8_t*)context->buffer)[usedspace++] = 0x80;

        if(usedspace > SHA256_SHORT_BLOCK_LENGTH) {
            memzero(((uint8_t*)context->buffer) + usedspace, SHA256_BLOCK_LENGTH - usedspace);

#if BYTE_ORDER == LITTLE_ENDIAN
            /* Convert TO host byte order */
            for(int j = 0; j < 16; j++) {
                REVERSE32(context->buffer[j], context->buffer[j]);
            }
#endif
            /* Do second-to-last transform: */
            sha256_Transform(context->state, context->buffer, context->state);

            /* And prepare the last transform: */
            usedspace = 0;
        }
        /* Set-up for the last transform: */
        memzero(((uint8_t*)context->buffer) + usedspace, SHA256_SHORT_BLOCK_LENGTH - usedspace);

#if BYTE_ORDER == LITTLE_ENDIAN
        /* Convert TO host byte order */
        for(int j = 0; j < 14; j++) {
            REVERSE32(context->buffer[j], context->buffer[j]);
        }
#endif
        /* Set the bit count: */
        context->buffer[14] = context->bitcount >> 32;
        context->buffer[15] = context->bitcount & 0xffffffff;

        /* Final transform: */
        sha256_Transform(context->state, context->buffer, context->state);

#if BYTE_ORDER == LITTLE_ENDIAN
        /* Convert FROM host byte order */
        for(int j = 0; j < 8; j++) {
            REVERSE32(context->state[j], context->state[j]);
        }
#endif
        MEMCPY_BCOPY(digest, context->state, SHA256_DIGEST_LENGTH);
    }

    /* Clean up state data: */
    memzero(context, sizeof(SHA256_CTX));
    usedspace = 0;
}

char* sha256_End(SHA256_CTX* context, char buffer[SHA256_DIGEST_STRING_LENGTH]) {
    sha2_byte digest[SHA256_DIGEST_LENGTH] = {0}, *d = digest;
    int i = 0;

    if(buffer != (char*)0) {
        sha256_Final(context, digest);

        for(i = 0; i < SHA256_DIGEST_LENGTH; i++) {
            *buffer++ = sha2_hex_digits[(*d & 0xf0) >> 4];
            *buffer++ = sha2_hex_digits[*d & 0x0f];
            d++;
        }
        *buffer = (char)0;
    } else {
        memzero(context, sizeof(SHA256_CTX));
    }
    memzero(digest, SHA256_DIGEST_LENGTH);
    return buffer;
}

void sha256_Raw(const sha2_byte* data, size_t len, uint8_t digest[SHA256_DIGEST_LENGTH]) {
    SHA256_CTX context = {0};
    sha256_Init(&context);
    sha256_Update(&context, data, len);
    sha256_Final(&context, digest);
}

char* sha256_Data(const sha2_byte* data, size_t len, char digest[SHA256_DIGEST_STRING_LENGTH]) {
    SHA256_CTX context = {0};

    sha256_Init(&context);
    sha256_Update(&context, data, len);
    return sha256_End(&context, digest);
}

/*** SHA-512: *********************************************************/
void sha512_Init(SHA512_CTX* context) {
    if(context == (SHA512_CTX*)0) {
        return;
    }
    MEMCPY_BCOPY(context->state, sha512_initial_hash_value, SHA512_DIGEST_LENGTH);
    memzero(context->buffer, SHA512_BLOCK_LENGTH);
    context->bitcount[0] = context->bitcount[1] = 0;
}

#ifdef SHA2_UNROLL_TRANSFORM

/* Unrolled SHA-512 round macros: */
#define ROUND512_0_TO_15(a, b, c, d, e, f, g, h)                                  \
    T1 = (h) + Sigma1_512(e) + Ch((e), (f), (g)) + K512[j] + (W512[j] = *data++); \
    (d) += T1;                                                                    \
    (h) = T1 + Sigma0_512(a) + Maj((a), (b), (c));                                \
    j++

#define ROUND512(a, b, c, d, e, f, g, h)                     \
    s0 = W512[(j + 1) & 0x0f];                               \
    s0 = sigma0_512(s0);                                     \
    s1 = W512[(j + 14) & 0x0f];                              \
    s1 = sigma1_512(s1);                                     \
    T1 = (h) + Sigma1_512(e) + Ch((e), (f), (g)) + K512[j] + \
         (W512[j & 0x0f] += s1 + W512[(j + 9) & 0x0f] + s0); \
    (d) += T1;                                               \
    (h) = T1 + Sigma0_512(a) + Maj((a), (b), (c));           \
    j++

void sha512_Transform(const sha2_word64* state_in, const sha2_word64* data, sha2_word64* state_out) {
    sha2_word64 a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, s0 = 0, s1 = 0;
    sha2_word64 T1 = 0, W512[16] = {0};
    int j = 0;

    /* Initialize registers with the prev. intermediate value */
    a = state_in[0];
    b = state_in[1];
    c = state_in[2];
    d = state_in[3];
    e = state_in[4];
    f = state_in[5];
    g = state_in[6];
    h = state_in[7];

    j = 0;
    do {
        ROUND512_0_TO_15(a, b, c, d, e, f, g, h);
        ROUND512_0_TO_15(h, a, b, c, d, e, f, g);
        ROUND512_0_TO_15(g, h, a, b, c, d, e, f);
        ROUND512_0_TO_15(f, g, h, a, b, c, d, e);
        ROUND512_0_TO_15(e, f, g, h, a, b, c, d);
        ROUND512_0_TO_15(d, e, f, g, h, a, b, c);
        ROUND512_0_TO_15(c, d, e, f, g, h, a, b);
        ROUND512_0_TO_15(b, c, d, e, f, g, h, a);
    } while(j < 16);

    /* Now for the remaining rounds up to 79: */
    do {
        ROUND512(a, b, c, d, e, f, g, h);
        ROUND512(h, a, b, c, d, e, f, g);
        ROUND512(g, h, a, b, c, d, e, f);
        ROUND512(f, g, h, a, b, c, d, e);
        ROUND512(e, f, g, h, a, b, c, d);
        ROUND512(d, e, f, g, h, a, b, c);
        ROUND512(c, d, e, f, g, h, a, b);
        ROUND512(b, c, d, e, f, g, h, a);
    } while(j < 80);

    /* Compute the current intermediate hash value */
    state_out[0] = state_in[0] + a;
    state_out[1] = state_in[1] + b;
    state_out[2] = state_in[2] + c;
    state_out[3] = state_in[3] + d;
    state_out[4] = state_in[4] + e;
    state_out[5] = state_in[5] + f;
    state_out[6] = state_in[6] + g;
    state_out[7] = state_in[7] + h;

    /* Clean up */
    a = b = c = d = e = f = g = h = T1 = 0;
}

#else /* SHA2_UNROLL_TRANSFORM */

void sha512_Transform(const sha2_word64* state_in, const sha2_word64* data, sha2_word64* state_out) {
    sha2_word64 a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, s0 = 0, s1 = 0;
    sha2_word64 T1 = 0, T2 = 0, W512[16] = {0};
    int j = 0;

    /* Initialize registers with the prev. intermediate value */
    a = state_in[0];
    b = state_in[1];
    c = state_in[2];
    d = state_in[3];
    e = state_in[4];
    f = state_in[5];
    g = state_in[6];
    h = state_in[7];

    j = 0;
    do {
        /* Apply the SHA-512 compression function to update a..h with copy */
        T1 = h + Sigma1_512(e) + Ch(e, f, g) + K512[j] + (W512[j] = *data++);
        T2 = Sigma0_512(a) + Maj(a, b, c);
        h = g;
        g = f;
        f = e;
        e = d + T1;
        d = c;
        c = b;
        b = a;
        a = T1 + T2;

        j++;
    } while(j < 16);

    do {
        /* Part of the message block expansion: */
        s0 = W512[(j + 1) & 0x0f];
        s0 = sigma0_512(s0);
        s1 = W512[(j + 14) & 0x0f];
        s1 = sigma1_512(s1);

        /* Apply the SHA-512 compression function to update a..h */
        T1 = h + Sigma1_512(e) + Ch(e, f, g) + K512[j] +
             (W512[j & 0x0f] += s1 + W512[(j + 9) & 0x0f] + s0);
        T2 = Sigma0_512(a) + Maj(a, b, c);
        h = g;
        g = f;
        f = e;
        e = d + T1;
        d = c;
        c = b;
        b = a;
        a = T1 + T2;

        j++;
    } while(j < 80);

    /* Compute the current intermediate hash value */
    state_out[0] = state_in[0] + a;
    state_out[1] = state_in[1] + b;
    state_out[2] = state_in[2] + c;
    state_out[3] = state_in[3] + d;
    state_out[4] = state_in[4] + e;
    state_out[5] = state_in[5] + f;
    state_out[6] = state_in[6] + g;
    state_out[7] = state_in[7] + h;

    /* Clean up */
    a = b = c = d = e = f = g = h = T1 = T2 = 0;
}

#endif /* SHA2_UNROLL_TRANSFORM */

void sha512_Update(SHA512_CTX* context, const sha2_byte* data, size_t len) {
    unsigned int freespace = 0, usedspace = 0;

    if(len == 0) {
        /* Calling with no data is valid - we do nothing */
        return;
    }

    usedspace = (context->bitcount[0] >> 3) % SHA512_BLOCK_LENGTH;
    if(usedspace > 0) {
        /* Calculate how much free space is available in the buffer */
        freespace = SHA512_BLOCK_LENGTH - usedspace;

        if(len >= freespace) {
            /* Fill the buffer completely and process it */
            MEMCPY_BCOPY(((uint8_t*)context->buffer) + usedspace, data, freespace);
            ADDINC128(context->bitcount, freespace << 3);
            len -= freespace;
            data += freespace;
#if BYTE_ORDER == LITTLE_ENDIAN
            /* Convert TO host byte order */
            for(int j = 0; j < 16; j++) {
                REVERSE64(context->buffer[j], context->buffer[j]);
            }
#endif
            sha512_Transform(context->state, context->buffer, context->state);
        } else {
            /* The buffer is not yet full */
            MEMCPY_BCOPY(((uint8_t*)context->buffer) + usedspace, data, len);
            ADDINC128(context->bitcount, len << 3);
            /* Clean up: */
            usedspace = freespace = 0;
            return;
        }
    }
    while(len >= SHA512_BLOCK_LENGTH) {
        /* Process as many complete blocks as we can */
        MEMCPY_BCOPY(context->buffer, data, SHA512_BLOCK_LENGTH);
#if BYTE_ORDER == LITTLE_ENDIAN
        /* Convert TO host byte order */
        for(int j = 0; j < 16; j++) {
            REVERSE64(context->buffer[j], context->buffer[j]);
        }
#endif
        sha512_Transform(context->state, context->buffer, context->state);
        ADDINC128(context->bitcount, SHA512_BLOCK_LENGTH << 3);
        len -= SHA512_BLOCK_LENGTH;
        data += SHA512_BLOCK_LENGTH;
    }
    if(len > 0) {
        /* There's left-overs, so save 'em */
        MEMCPY_BCOPY(context->buffer, data, len);
        ADDINC128(context->bitcount, len << 3);
    }
    /* Clean up: */
    usedspace = freespace = 0;
}

static void sha512_Last(SHA512_CTX* context) {
    unsigned int usedspace = 0;

    usedspace = (context->bitcount[0] >> 3) % SHA512_BLOCK_LENGTH;
    /* Begin padding with a 1 bit: */
    ((uint8_t*)context->buffer)[usedspace++] = 0x80;

    if(usedspace > SHA512_SHORT_BLOCK_LENGTH) {
        memzero(((uint8_t*)context->buffer) + usedspace, SHA512_BLOCK_LENGTH - usedspace);

#if BYTE_ORDER == LITTLE_ENDIAN
        /* Convert TO host byte order */
        for(int j = 0; j < 16; j++) {
            REVERSE64(context->buffer[j], context->buffer[j]);
        }
#endif
        /* Do second-to-last transform: */
        sha512_Transform(context->state, context->buffer, context->state);

        /* And prepare the last transform: */
        usedspace = 0;
    }
    /* Set-up for the last transform: */
    memzero(((uint8_t*)context->buffer) + usedspace, SHA512_SHORT_BLOCK_LENGTH - usedspace);

#if BYTE_ORDER == LITTLE_ENDIAN
    /* Convert TO host byte order */
    for(int j = 0; j < 14; j++) {
        REVERSE64(context->buffer[j], context->buffer[j]);
    }
#endif
    /* Store the length of input data (in bits): */
    context->buffer[14] = context->bitcount[1];
    context->buffer[15] = context->bitcount[0];

    /* Final transform: */
    sha512_Transform(context->state, context->buffer, context->state);
}

void sha512_Final(SHA512_CTX* context, sha2_byte digest[SHA512_DIGEST_LENGTH]) {
    /* If no digest buffer is passed, we don't bother doing this: */
    if(digest != (sha2_byte*)0) {
        sha512_Last(context);

        /* Save the hash data for output: */
#if BYTE_ORDER == LITTLE_ENDIAN
        /* Convert FROM host byte order */
        for(int j = 0; j < 8; j++) {
            REVERSE64(context->state[j], context->state[j]);
        }
#endif
        MEMCPY_BCOPY(digest, context->state, SHA512_DIGEST_LENGTH);
    }

    /* Zero out state data */
    memzero(context, sizeof(SHA512_CTX));
}

char* sha512_End(SHA512_CTX* context, char buffer[SHA512_DIGEST_STRING_LENGTH]) {
    sha2_byte digest[SHA512_DIGEST_LENGTH] = {0}, *d = digest;
    int i = 0;

    if(buffer != (char*)0) {
        sha512_Final(context, digest);

        for(i = 0; i < SHA512_DIGEST_LENGTH; i++) {
            *buffer++ = sha2_hex_digits[(*d & 0xf0) >> 4];
            *buffer++ = sha2_hex_digits[*d & 0x0f];
            d++;
        }
        *buffer = (char)0;
    } else {
        memzero(context, sizeof(SHA512_CTX));
    }
    memzero(digest, SHA512_DIGEST_LENGTH);
    return buffer;
}

void sha512_Raw(const sha2_byte* data, size_t len, uint8_t digest[SHA512_DIGEST_LENGTH]) {
    SHA512_CTX context = {0};
    sha512_Init(&context);
    sha512_Update(&context, data, len);
    sha512_Final(&context, digest);
}

char* sha512_Data(const sha2_byte* data, size_t len, char digest[SHA512_DIGEST_STRING_LENGTH]) {
    SHA512_CTX context = {0};

    sha512_Init(&context);
    sha512_Update(&context, data, len);
    return sha512_End(&context, digest);
}
